1. Field of the Invention
The invention relates to a method and to an apparatus for maintaining a constant pressure, which depends on the aqueous humour, inside the eye of an organism, in which the aqueous humour circulating from the posterior chamber to the anterior chamber is removed via the circular canal of Schlemm and via the upstream trabecular tissue.
2. Discussion of Prior Art
For perfect functioning of the eye it is necessary, inter alia, for the pressure of the aqueous humour which is continuously being renewed and circulating between the posterior chamber and the anterior chamber to be balanced in such a way that the outflow and inflow of the aqueous humour are the same, and the outflow of the aqueous humour via the trabecular tissue upstream of the Schlemm's canal is ensured.
Disturbances of the outflow of aqueous humour may occur, for example, when the filtration angle constricts the access to Schlemm's canal in the form of slit, or else when there are pathological changes, which prevent the passage of the aqueous humour, in the trabecular tissue upstream of the Schlemm's canal. If the outflow of the aqueous humour is less than its inflow, the pressure inside the eye increases, which produces the visual disturbance which is known under the name "glaucoma" and often leads to blindness.
Pharmaceutical and surgical methods are known for the treatment of a pathological Schlemm's canal which prevents pressure equalisation, and of the trabecular tissue. The generally known pharmaceutical method may lead to unwanted, troublesome side effects in the patient. The method which opens the canal of Schlemm and the trabecular tissue and is performed surgically or with a laser has not led to the required success in the long term either because regeneration of the tissue closes the openings in the trabecular tissue again after a relatively short time.